Rubber stamp.



G G. GIBSON. RUBBER STAMP.

APPLIOATION FILED 111:0. so, 1909.

Patented Oct. 11,1910.

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"UNITED STATES PATENT OFFICE.

CALDER C. GIBSON, OF BUFFALO, NEW YORK.

RUBBER STAMP.

To all whom it may concern:

3e it known that I, CALIiER C. GIBSON, a citlzen of the United States,residing at Buffalo, in the county of Erie and State of New York, haveinvented a certain new and useful Improvement in Rubber Stamps, of whichthe followin is a specification.

This invention relates to improvements in rubber stamps and particularlyto the construction of the cushion or base located between the block orsupport and the type strip.

The principal objects of the invention are to secure a very soft andresilient cushion and to enable cushions of a desired size to be readilycut from a cushion strip or sheet. Toaccomplish these objects the rubberstrip or sheet from which the cushions are cut is formed of twosuperimposed sheets of rubber of differing quality vulcanized togetherto form an integral structure, one of said sheets being of very softporous or honeycombed rubber, known to the trade as sponge rubberand theother being of the ordinary commercial quality non-porous rubber. Thesponge rubber sheet is cut into a series of blocks by a series of thinblades arranged so as to out both longitudinally extending andtransversely extending grooves therein. The sheet of ordinary rubber ispro-vided with a series of recesses or pockets which are formed thereinin the outer surface thereof during the process of vulcanizing the twosheets to gether and are sufficiently deep to extend up Within thesponge rubber sheet.

The invention also relates to certain details of construction of thecushion or base strip, which will be hereinafter described and perhapsclaimed reference being had to the accompanying drawings in which,

Figure 1 is an end View of a hand stamp partially in section providedwith the improved cushion or base. Fig. 2 is a detached top view of thecushion or base. Fig. 3 is a detached bottom View of the cushion orbase. Fig. at is a transverse section on line a a, Fig. 2. Fig. 5 is atransverse section on line b b, Fig. 2.

In referring to the drawings in detail like numerals designate likeparts.

In Fig. 1 a hand rubber stamp is shown having a Wooden supporting block1 provided with a handle 2. The bottom surface of the block 1 isrecessed to secure a cushion or base for the stamp proper which is se-Specification of Letters Patent.

Application filed December 30, 1909.

Patented Oct. 11, 1910.

Serial No. 535,643.

cured therein by cement or in any other suitable way.

The cushion or base is constructed so as to provide a very soft andresilient cushioning effect to take care of any slight inequalities ofsurface in the article to be printed upon and also to receive anindependent pneumatic cushion to supplement the action of the resilientcushion.

The soft resilient cushioning effect is obtained by utilizing a fairlythick outer sheet of exceedingly soft porous or honeycombed rubber knownas sponge rubber, and the inner pneumatic action is secured by attachingto the under surface of the sponge rubber a sheet of ordinary non-porousrubber. These two sheets are vulcanized together to form an integralsheet and at the same time are pressed into form between dies which alsocut the sponge rubber portions in blocks and form recesses or pockets inthe ordinary rubber.

The sponge rubber portion is indicated in the figures of the drawings bythe numeral 3, and the ordinary rubber portion by the numeral 4.

By referring to Figs. 4 and 5, it will be noted that the indentations orgrooves 5 which separate the sponge rubber portion 3 into blocks extendcompletely through the same, so that the sponge rubber is actuallycompletely separated into a plurality of parts which are only heldtogether by the vulcanization of their side surface to the ordinaryrubber portion 4. The advantage of this is that it is not necessary tocut the sponge rubber at all in cutting a base of any desired size.

The pockets 6 in the ordinary rubber which may be of any desired shapeor depth are formed therein during the process of vulcanization andforce the ordinary rubber up into the songe rubber securing aninterlocking eifdct which provides more surface for vulcanization andsecures the two sheets inseparably together.

WVhen the base is secured in place in the stamp support or block 1, asshown in Fig. 1, the pockets provide a series of air spaces which forminner pneumatic cushioning means. a

In the adaptation of the invention shown in the accompanying drawings,the indentations or grooves are cut through the sponge rubber on oneside of the base sheet and the pockets 6 are formed in the ordinaryrubber 'on the opposite side of the sheet and are so sized, shaped andlocated that each pocket extends within one of the blocks formed by theindentations or grooves. By this means each block has an outer very softresilient cushion of sponge rubber and an inner pneumatic or air cushionlocated behind the sponge rubber which gives a double cushioning effect.

A rubber type plate 7, having formed thereon the desired printingmatter, is secured by cement to the outer face of the sponge rubber asshown in Fig. 1. The ordinary rubber sheet is thinner than the spongerubber sheet, being in the adaptation shown about one fifth of the totalthickness of the completed cushion, and when pressed into shape is of analveolated form owing to the multiplicity of its pockets. To cut a baseof the desired size from this improved sheet, it is only necessary tocut through the ordinary rubber, which can be out easily and accuratelywith a wet knife, placing the knife in the bottom of the grooves 5 whichextend completely through the sponge rubber.

The great advantage of this improved form of cushion base sheet is thatthe easy soft resiliency of the sponge rubber is secured together withthe desirable pneumatic action of air pockets.

I claim.

1. In a device of the class described, a

cushion composed of superimposed sheets of sponge rubber and ordinaryrubber vulcanized together to form an integral structure; one of saidsheets being formed with grooves which completely sever the sheets intoseparate sections and the other of said sheets being formed withrecesses which extend beyond the bottom of the groove and into thesections of the first mentioned sheet.

2. In a device of the class described, a support, a cushion secured tosaid support and having an outer portion of soft porous rubber known assponge rubber; said outer portion being divided by longitudinal andtransverse grooves into blocks, and an inner portion of ordinary rubberprovided with recesses forming air pockets; each of said recessesextending into one of the blocks of the outer portion, and a type platesecured to the outer surface of the outer plate.

3. In a device of the class described, a cushion composed of vulcanizedtogether sheets of sponge rubber and non-porous rubber; one of saidsheets being provided with dividing imlentations which extend to thesurface of the other sheet and the other of said sheets being providedwith pockets which extend into the first mentioned sheet between theindentations thereof.

CALDER c. "oIBsoN.

Witnesses L. M. SANGSTER, Gnonon A. NEUBAUER.

